Back in 1977, Goodyear introduced the Tiempo, the first tire dubbed all-season. The idea was simple and alluring: Instead of dealing with the hassle of switching between snow and summer tires as the seasons change, drivers could use one tire all the time. Sales skyrocketed and other companies quickly followed suit. These days nearly all vehicles sold in the United States are fitted with all-season tires from the factory, and 97.5 percent of replacement-tire sales are the same. But is that such a good idea? Actually, no. It turns out that all-season tires are fine in warmer months, but in the snow, they lack traction compared with dedicated snow tires. And that means that the millions of drivers who make do with all-season tires in the winter months are driving cars that aren't as safe as those shod with tires designed for icy conditions.

We know because we traveled to northern Minnesota, home of some of the nation's harshest conditions, to test the claim of the all-season tire. And since all-wheel drive is rapidly becoming a common option, we also tested the notion that the feature is a suitable substitute for snow tires. Our assumption was that, while AWD improves some aspects of winter performance, it doesn't help a car turn or stop, and the added weight of the mechanical bits can actually be a disadvantage. Common sense and physics suggested this to be true, but nothing proves a point like data. And the best way to gather data on winter-tire performance is to find yourself an icy, snowy proving ground.

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Ice Driving

There's something foreboding about traveling to a place so cold it's called the Ice Box, but Baudette, Minn., was the perfect place to run our experiments. The sprawling Automotive Enviro Testing facility there specializes in frigid-weather testing for many large auto manufacturers. With a five-month winter season, the facility can maintain enormous snow and ice surfaces kept within strict tolerances by GPS-controlled tractors towing custom-built ice- and snow-grooming systems—basically the world's largest Zambonis.

To set a level playing field, we brought along two nearly identical four-cylinder 2011 Chevy Equinoxes—one optioned with front-wheel drive, the other with AWD. We ran both through a series of tests to measure acceleration, braking, hill-climb and turning ability. The cars were first outfitted with Goodyear all-season tires, then we ran the tests again with Goodyear snow tires. We ran each test numerous times and then averaged the results. To minimize the variables, the same driver performed all the tests, and the traction- and stability-control systems were left on. Data collection was completed with the industry standard VBOX—a GPS and accelerometer-based data logger.

The Bottom Line

In a contest between all-season and winter tires driven on snow and ice, the latter won the day. Although the year-round rubber performed admirably, it's clear in all situations that with either FWD or AWD there's a substantial advantage to having proper rubber under you. The results were especially striking during braking and cornering, when snow tires improved performance by up to 5 percent and 20 percent, respectively.

Buying and living with winter tires isn't that much of an inconvenience, but there are some guidelines you should follow:

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If you live anywhere north of the Mason-Dixon line, it's probably worthwhile to invest in winter tires.

Make sure you buy four tires; skimping and putting winter tires only on the drive end of the car will result in unpredictable handling and could be dangerous.

If you'd rather not remount your tires each season, pick up a separate set of inexpensive steel wheels for permanent winter-tire duty. (This also keeps expensive alloy wheels from getting damaged in harsh, salty winter conditions.)

Swap to winter tires around Thanksgiving and back to all-season or summer tires around Easter—winter tires' softer rubber compounds wear quickly in warmer temperatures.

Store off-season tires in a cool, dry area out of the sun, and consider wrapping them in black plastic bags to reduce oxidation.

Keep in mind that having two sets of tires isn't doubling the expense, it's halving the wear. You'll have twice the number of tires but buy new ones half as often.

Remember, fancy new tires or not, the standard winter driving advice still applies: Slow down, double your following distances, anticipate traffic changes ahead, and give yourself extra time to get where you're going. Good luck out there!

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